In the apparatus, not only are screw elements fitted on the supporting shafts, but also kneading blocks and similar processing elements for converting an optimum of the driving energy into kneading and mixing power.
To distribute the resin along the screw as evenly as possible during processing, DE 31 34 479 A1 discloses a screw extruder wherein a triple-threaded screw is divided into disks that are fitted on the supporting shaft at a progressive angular offset from each other. The resulting faces on the disks must be provided with central shoulders halfway up so that the relevant faces can move past each other freely upon rotation of the screw.
Due to geometrical relations, the triple-threaded screw machine can only be executed up to a maximum ratio of outside screw diameter to screw core diameter of less than 1.3661. At the same time, both the effective screw surface on the face and the surface of the intermesh zone are relatively small, making the processing efficiency practically negligible.
Due to the numerous disks, the known apparatus moreover involves considerable production effort. But, above all, the many possible angular positions of the disks easily lead to errors when fitting them on, in particular when several screws are to be fitted. Also, the disks considerably reduce the bending strength of the screw shaft for transfer of radial forces, which increases partial wear and risk of breakage.
The problem of the invention is to provide a screw machine that can be equipped with screw elements like a conventional screw machine, but leads to optimal homogenization with optimal conversion of its driving energy.